Time-dependent Reliability Analysis of a Nonrepairable Multifunctional System Containing Multifunctional Components

A multifunctional system is designed to provide several required functions to accomplish one task or a series of tasks, and the system will fail when at least one function is totally lost. Such a system may contain multifunctional components, for which the lost function of a component can be restored by the same function of another component. To ensure the reliability of the system under a limited budget, the redundancy level of each function must be wisely selected. Moreover, the start-up strategy that determines which components and their functions are to be activated first has a significant impact on system reliability when no maintenance can be performed during operation. In this paper, the lifetimes of components and their functions are assumed to follow exponential distributions. The time-dependent reliability of the system is evaluated by a continuous-time Markov chain model once the start-up strategy and the redundancy levels of components are determined. Two experiments on an onsite monitoring system involving multiple unmanned aerial vehicles are provided to illustrate the effects of failure rates of components and functions, start-up strategy, and redundancy levels on the reliability of the system. To maximize system reliability, the failure rates of components and functions need to be well balanced. Moreover, a start-up strategy involving a less number of activated components results in a higher system reliability over time for the system with given redundancy levels.